Scientists at USDA’s Subtropical
Horticulture Research Laboratory in
Miami, FL, are testing a bait of sugar,
yeast and abamectin as an alternative to
malathion bait spray for Caribbean fruit fly
control in citrus and other crops. They
plan to test the bait against
Mediterranean fruit fly, also. The
efficiency of this product on Caribe fly
suggests possibilities for use on Mexican
fruit fly in citrus in Texas, but such testing
has not been announced.

The USDA is applying for a pate nt for
this bait and is seeking a cooperative
research and development deal to
commercialize the product. Abamectin is
the active ingredient in Merck’s Agri-
Mek® currently being used for mite and
leafminer control in citrus.

CITRUS PESTS & THAILAND-

I have recently had requests from
both TDA and USD A about an annotated
listing of insects and diseases that
presently ex ist in Texas citrus. The TDA
request was apparently initiated in
response to the USDA request. While
the reasons for these inquiries were
neither offered nor requested,
subsequent conversation with Dr. Vic
French and others suggested a possible
link to Thailand.

More recently, I learned that Sunkist
Growers began shipping navel oranges
to Thailand back in January a fter years of
effort by U.S. and Thai officials to work
out some problems of phytosanitary
regulations and import tariffs that were
effectively excluding any citrus
importation into Thailand. Hopefully,
Texas citrus can make the grade for
export to Thailand in the coming season.

CROP DISPOSITION-

The industry heard an aw ful lot about
sheepnose last season, with real horror
stories of packouts as low as 30 percent
on some orchards. But the problem was
not so severe as one would th ink, at least
based upon market disposition of the
crop. Fresh market Texas grapefruit
accounted for 64.26 percent of
productionin 1995-96, with 35.74 percent
processed. By contrast, fresh utilization
in the 1994-95 season was only 68.67
percent, with 31.32 percent processed.
Thus, it would appear that sheepnose
and all other grade-lowering factors
accounted for a decline of only about 4.4
percent.

Early oranges, including navels, were
marketed 81.16 percent fresh and 18.84
percent processing; while Valencias went
91.96 percent fresh and 8.04 percent
processing.

If you have the inclination, and the
records, you can compare these values
to your packouts, since these are the
industry average packouts.

POTENTIAL CITRUS WATER USE-

Based upon historical records, I
indicated that citrus would average
needing about 1.2 inches of water per
week during May. Because of higher
maximum, minimum and mean
temperature averages during May, pan
evaporation was higher than normal.
Since pan evaporation was up, so was
potential evapotranspiration, i.e. citrus
water requirement during May was up
about 0.2 inch (weekly average).

Data for June indicates about 1.5 to
1.6 inches of water use weekly by citrus,
with 1.6 to 1.7 inches per week in both
July and August. If temperatures remain
slightly higher than normal, so too will
citrus water use during these months.
Because of June rains in the lower
Valley, both evaporation and
evapotranspiration should be at or below
normal for the month in that area.

POST-HARVEST LOSSES-

The Texas citrus industry has
experienced some significant losses to
post-harvest decay over the last few
years-some years being worse than
others. Probably no one in the industry
fully appreciates the magnitude of the
problem exc ept shippers and a couple of
researchers who have studied the
problem over the last couple of years.

In the June newsletter from the Citrus
Center, Dr. Mani Skaria reported the
results of a test last seas on involving ‘Rio
Red’ grapefruit fr om a single orchard and
a single harvest. Basically the harvest
was divided among four packinghouse
and an in-the-field pack. All lots were
shipped UPS to six interstate and four
intrastate locations, then returned to the
Citrus Center for evaluation.

Regardless that this test occurred in
late season and the fruit was not
refrigerated, the losses are appalling-a
minimum of one-third of the fruit from the
packinghouses rotted. While the
numbers were not as bad, I consider the15 to 20 percent l osses that
occurred on field-packed fruit to be excessive.

To summarize this work, the losses
from the field-packed fruit occurred from
damages sustained by the fruit while still
on-tree, during harvest and boxing and
during transit. The four lots from the
packinghouses experienced those same
damages on-tree, during harvest and
during transit, plus additional damages
that occurred during hauling and during
packing.

Thus, if you subtract the losses
sustained by the field-packed fruit from
that of the packinghouse, you still get 15
to 20 percent loss (minimum) that is
solely due to hauling and packinghouse
operations (the maximum would be in the
range of 30 to 60 percent).

TEMPORARY RELIEF-

The rains across the middle and
lower Valley during the last half of June
provided much-needed relief for our
dwindling water reserves, but such relief
is short-lived at best since there was no
significant rain in the watershed.
Moreover, many orchards in the upper
Valley were not blessed with even a little
rainfall.

From an over all agricultural irrigation
standpoint, demand should be in a lull
anyway, as grain is completed, corn
should be finished and there’s’s little in
the way of vegetables, leaving only
pasture, cotton, cane and citrus until
planting of fall vegetables and corn
starting in August. However, several
irrigation districts are already out of water
or are very close to it. In addition,
there’s talk of a possible negative
allocation, i.e., we may have to give back
part of the allocation that hasn’t been
used as yet.

Too bad we can’t capture and store
the runoff from last week’s rai ns for future
irrigation use.

CURRENT TOPICS-

While irrigation demand has
slackened a little in the middle and lower
Valley, unless rains return during July,
irrigation of those orchards will resume
shortly, given water availability.

Some orchards were in serious
trouble at mid-June, as I noted several
orchards that were wilting daily and a
couple with trees in permanent wilt (from
which they will not recover). Hopefully,
the rains hel ped some of those with daily
wilt sufficiently that they can go another
several weeks in hopes of additional
rains.

Asian citrus leafminer damage this
year continues to be relatively
inconspicuous, even on the current flush
of orchards that were being regularly
irrigated. Stressed orc hards should push
a growth flush in response to the recent
rain, but it’s anybody’s guess as to
whether leafminer will explode on it.

Other pests need monitoring
regularly, inasmuch as it is nearing the
time when post-bloom Temik® and other
miticides should start to break, so rust
mites could increase quickly. Too, July is
the usual time when red scale starts to
build.

For the summer spray, when it
becomes necessary, oil is hard to beat
for cost and effectiveness if applied
properly with respect to weather. It
works very well on mites, scales and
greasy spot , while being environmentally
friendly. To reduce potential phytotoxicity
and to enhance th e summer spray, lower
rates of oil can be supplemented with a
miticide, scalicide and/or fungicide. Oil
should not be applied to droug ht-stressed
trees.

FREEZING GRAPEFRUIT
SECTIONS-

I credit Dr. Bill Grierson for this idea
to preserve grapefruit in the freezer for
later enjoyment, which was recently
printed in Citrus Industry (May, 1996, p.
26). A couple of Winter Texans indicate
good success with the method, though
they claim no proprietary rights to the
origin of the idea.

Freezer bags work nicely, though
they can be a bit troublesome to fill. To
obtain the grapefruit sections, either use
the serrated grapefruit spoon to extract
them just as you would if you were going
to eat a grapefruit half. Another way to
get sections is the commercial way of
sectioning-cut off both ends, then cut off
the remaining rind with several knife
strokes (each cutting into the section
slightly to remove the outer membrane).
Then separate the sections from the
membrane.

Place the spoon-sized or the
commercial-sized sections into plastic
freezer bags, pour the extra juice over
the sections, and seal the bags. Remove
the air from the bag at closure for best
results. Freeze, then thaw when you
want them. They’ll last for months with
no discernible flavor loss.

THE INFORMATION GIVEN HEREIN IS FOR EDUCATIONAL PURPOSES ONLY.
REFERENCE TO COMMERCIAL PRODUCTS OR TRADE NAMES IS MADE WITH THE UNDERSTANDING
THAT NO DISCRIMINATION IS INTENDED AND NO ENDORSEMENT BY THE COOPERATIVE
EXTENSION SERVICE IS IMPLIED.